The catalog pg_shseclabel stores
security labels on shared database objects. Security labels can
be manipulated with the SECURITY LABEL command. For an
easier way to view security labels, see Section 47.65.

See also pg_seclabel, which performs a similar
function for security labels involving objects within a single
database.

Unlike most system catalogs, pg_shseclabel is shared across all databases of
a cluster: there is only one copy of pg_shseclabel per cluster, not one per
database.